2/2003 K4（LINEAR）彗星中的水
Water in Comet 2/2003 K4 (LINEAR) with Spitzer
摘要：
我们提出了敏感的5.5至7.6微米的光谱彗星C/2003 K4（线性）获得2004年7月16日（r_{h} = 1.760 AU，Delta_{Spitzer} = 1.409 AU，相位角35.4度）与斯皮策太空望远镜。水的nu_{2}振动带以高信噪比（> 50）被检测到。对最佳光谱的模型拟合得到水的邻对位比为2.47 ± 0.27，对应于自旋温度为28.5^{+6.5}-3.5} K。在不同的偏移位置获得的光谱表明，旋转温度随着距离核，这是一致的演化从热荧光平衡的增加而降低。推断的产水率为（2.43 +/- 0.25）\times 10^{29} molec。s^{-1}。光谱没有显示出任何证据的排放从多环芳烃和碳酸盐矿物，相反的结果报告彗星9 P/坦普尔1和C/1995 O 1（海尔-波普）。然而，在7.3微米附近观察到残留发射，其来源仍然不明。
英文摘要：
We present sensitive 5.5 to 7.6 micron spectra of comet C/2003 K4 (LINEAR) obtained on 16 July 2004 (r_{h} = 1.760 AU, Delta_{Spitzer} = 1.409 AU, phase angle 35.4 degrees) with the Spitzer Space Telescope. The nu_{2} vibrational band of water is detected with a high signal-to-noise ratio (> 50). Model fitting to the best spectrum yields a water ortho-to-para ratio of 2.47 +/- 0.27, which corresponds to a spin temperature of 28.5^{+6.5}_{-3.5} K. Spectra acquired at different offset positions show that the rotational temperature decreases with increasing distance from the nucleus, which is consistent with evolution from thermal to fluorescence equilibrium. The inferred water production rate is (2.43 +/- 0.25) \times 10^{29} molec. s^{-1}. The spectra do not show any evidence for emission from PAHs and carbonate minerals, in contrast to results reported for comets 9P/Tempel 1 and C/1995 O1 (Hale-Bopp). However, residual emission is observed near 7.3 micron the origin of which remains unidentified.
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